<!DOCTYPE html>
<html>
<head>
<!-- Tests that `counter` works. -->
<style>
h1, h2, h3 {
    font-size: 24px;
}
</style>
</head>
<body>
<h1>1. Foo</h1>
    <h2>1.1. Boo</h2>
    <h2>1.2. Quux</h2>
        <h3>1.2.1. Blah</h3>
<h1>2. Bar</h1>
    <h2>2.1. Boo</h2>
    <h2>2.2. Quux</h2>
<h1>3. Baz</h1>
</body>
</html>

